This invention relates in general to accumulators for conveyor systems and in particular to an improved structure for an accumulator having vertically movable shelves.
Conveyors are well known devices which are commonly used in production line situations to transport articles from one location to another. For example, a conveyor may be used to transport cartons of a product from an upstream filling station, wherein the cartons are filled with the product and sealed, to a downstream packaging station, wherein the sealed cartons are packaged into larger shipping containers. Many conveyor system structures are known in the art for accomplishing this basic function.
Usually, the conveyor system is designed to provide a continuous flow of articles from the upstream station on the production line to the downstream station. However, occasionally, it becomes necessary to halt this continuous flow of articles. For example, the flow of articles may need to be stopped because one or more of the articles becomes jammed in the production line and must be cleared. Alternatively, the flow of articles may need to be halted because the downstream processing equipment is temporarily unable to accept the continued flow of articles. To accommodate this, some known conveyor systems are provided with a control system which simply ceases the flow of articles therethrough when this occurs. This is frequently undesirable, though, because it requires that the upstream equipment on the production line cease operation until the problem located downstream is corrected.
To address this problem, it is known to provide one or more accumulators midstream within a conveyor system. An accumulator is a device which is typically located between first and second individual conveyors in a conveyor system. When the production line is operating normally, the accumulator receives products from the first conveyor and merely transports them therethrough to the second conveyor. However, when a problem occurs in the downstream portion of the production line, such as described above, the accumulator receives products from the first conveyor and temporarily stores them therein until the problem is corrected. Thus, the accumulator functions to temporarily prevent the flow of the articles downstream thereof, while permitting the upstream portion of the production line to continue, at least temporarily, in normal operation.
Many different accumulator structures are known in the art. One type of accumulator structure is known as a horizontal accumulator. A typical horizontal accumulator includes a plurality of horizontally spaced, parallel storage paths. One or more entrance gates are provided for directing the flow of products from the first conveyor to one of the storage paths as necessary. In this manner, the flow of products downstream is temporarily prevented. When it is desired to resume the flow of products downstream of the horizontal accumulator, one or more exit gates are opened so as to direct the stored products from the storage paths into the second conveyor. While horizontal accumulators of this general type are effective for temporarily preventing the flow of products therethrough, they have been found to be inefficient because of their physical size. Specifically, the parallel storage paths of these horizontal accumulators occupy an undesirable large amount of floor space in the facility in which they are used.
To minimize this floor space problem, a second type of accumulator structure, known as a vertical accumulator, has been developed. A typical vertical accumulator includes a plurality of vertically spaced, parallel storage paths. Articles passing through the vertical accumulator are received from the first conveyor and stored in groups on shelves. When a first shelf is filled with a plurality of articles, it is elevated above the vertical height of the first and second conveyors to permit a second shelf to be filled in a similar manner. When it is desired to return the stored products to the conveyor system, the shelves are sequentially lowered to permit the articles to be fed to the second conveyor. Thus, it can be seen that vertical accumulators occupy a relatively small amount of floor space in the facility in which they are used and, therefore, are generally preferable to the horizontal accumulators described above.
Many different vertical accumulator structures are known in the art. In a first type of vertical accumulator, the articles are lifted above the vertical height of the conveyor system by opposed lifting flanges which engage the peripheral edges of the articles. This type of vertical accumulator is undesirable because the spacing between the lifting flanges must be varied when articles of varying size are to be stored. In a second type of vertical accumulator, the articles are lifted above the vertical height of the conveyor system by shelves formed from a plurality of individual fingers. The fingers pass upwardly between cantilevered rollers of the conveyor to lift the articles upwardly. The capacity of both of these types of vertical accumulators is limited by the vertical space available above the conveyor.
A third type of vertical accumulator uses an endless member mounted about a conveyor section. A plurality of cantilevered shelves are attached at spaced intervals to the endless member, while a shroud is disposed about the endless member and shelves above the conveyor section. When accumulation of the articles is desired, the endless member is rotated, causing the cantilevered shelves to sweep a row of the articles laterally off of the conveyor section and upwardly against the surrounding shroud. The shroud functions to retain the articles on the shelves as they are swept in an arcuate path off of the conveyor section and upwardly. As the endless member is further rotated, additional shelves can be stored with products. Because the shroud extends over the upper portion of the vertical accumulator, the shelves of stored products may be swept in an arcuate manner over such upper portion and downwardly on the other side of the vertical accumulator. As a result, this type of vertical accumulator has a relatively large storage capacity. However, it has been found that this type of vertical accumulator is not easily adaptable for use with articles of varying size because such articles must engage the enclosing shroud to function as described above. As a result, the shroud must be re-positioned each time articles of a different size are to be accumulated. This can be a difficult and time consuming operation. Thus, it would be desirable to provide an improved structure for an accumulator which can easily accommodate articles of varying size.